Question: What is the diameter of the Arecibo Observatory which applies to Illuminated aperture?
Paraphrase: How big is the opening of the Arecibo Observatory?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q44547 p:P2386 ?s . ?s ps:P2386 ?obj . ?s pq:P518 wd:Q40782571 }